Litvinovich wrote on Telegram she was detained as she was leaving her apartment in Moscow.

In a video statement on Facebook, Litvinovich called on Russians across the country not to be afraid and to protest Russia's attack on Ukraine.

"I know that many of you right now feel desperate, powerless, and ashamed over the attack by [President] Vladimir Putin on the friendly people of Ukraine. But I call on you not to be desperate and come out to the central squares of your cities at 7 p.m. today and clearly and explicitly say that we, the people of Russia, are against the war unleashed by Putin," Litvinovich said.

the Investigative Committee, meanwhile, warned citizens against taking part in anti-invasion protests.

"The Investigative Committee of Russia warns of responsibility for holding unauthorized actions and participating in uncoordinated events," the committee said in a message on its official web page.

However, in many cities across Russia, Omsk, Khabarovsk, Irkutsk, Novosibirsk, Astrakhan, and Saratov, people held single-person pickets -- which do not require preliminary permission from the authorities -- to demand that Russian authorities immediately stop the military attack on Ukraine.

Many of the picketers were detained by police.

In neighboring Kazakhstan, police in the Central Asian state's largest city, Almaty, arrested several activists who rallied in front of the Russian Consulate condemning the war in Ukraine.

In another Central Asian country, Kyrgyzstan, dozens of activists picketed the Russian Embassy on February 24, protesting Russia's attack on Ukraine.

With reporting by Siberia.Realities, Idel.Realities, and RFE/RL's Kazakh Service